When performing inspection, shape recognition, and other such processing by image processing a picture of an object to be inspected taken with a CCD camera, focusing the CCD camera on the object to be inspected is essential for performing imaging with good accuracy.
However, when imaging different surfaces of an object to be inspected, and when the optical path lengths from a plurality of objects to be inspected to a CCD camera differ, if the camera is focused on a portion of the objects to be inspected, other portions thereof are out of focus.
In other words, the problem, as shown in FIG. 33, is that when attempting to image with 1 CCD camera 2 planes A, B that are different distances from the CCD camera, if the camera is focused on plane A, then the pattern of plane B is out of focus.
Further, the inspection of a semiconductor package is an inspection that uses an imaging device such as the above-mentioned CCD camera. As inspection items of this semiconductor package, there are:
(1) Inspecting the coplanarity of leads; PA1 (2) Inspecting for lead pitch variations, displacement; and PA1 (3) Inspecting for missing characters, blurring, and displacement of marks stamped on the upper surface of a package.
Here, when inspecting the coplanarity of the leads of an IC package, such as a surface mount-type SOP (small outline package), an IC side image, which images an IC from the side as shown in FIG. 35(b), is required (to find IC that have lifted leads as shown in FIG. 34).
Accordingly, when performing a lead coplanarity inspection such as this, in the past, a camera was provided to the side of an IC as shown in FIG. 35(a). The technique, whereby a camera is provided to the side of an IC like this, enables an IC image to be suitably captured when the IC is placed on top of a flat tray.
However, when an IC is contained in embossed tape E as shown in FIG. 36, it is impossible to obtain an IC side image by providing a camera to the side of the IC. Embossed tape E is used here to stock a plurality of ICs following production thereof, and is made from a black plastic material. Further, a square-shaped step is formed so as to enable each IC to be housed separately in a plurality of juxtaposed IC containers EA. Furthermore, when stocking ICs, embossed tape E is wound on a reel.
That is, when embossed tape is utilizes as an IC stocker, a process is established so that an IC can be housed in embossed tape following production, but when performing a lead coplanarity inspection in accordance with conventional technology, the need to add a process in which an IC is placed on top of a flat tray so that a camera can be provided to the side of the IC is disadvantageous from the standpoint of production efficiency. Accordingly, an inspection technique for enabling a lead coplanarity inspection to be performed in a state in which an IC is housed as-is in the embossed tape is desirable.
However, as described above, there are other inspections involved in a semiconductor package inspection beside the lead coplanarity inspection, such as inspecting for missing characters, blurring and displacement of the markings stamped on the upper surface of a package. To carry out these inspections, a plan view of the upper surface of a semiconductor package is required. Accordingly, in the past, the trouble was that since cameras were provided both to the side and above a semiconductor, and each of the above-mentioned inspections was performed on the basis of image data of these cameras, numerous cameras were required, costs were high, a lot of space was required for the cameras, and it was difficult to adjust numerous cameras properly.
With the foregoing in view, it is an object of the present invention to provide an inspection object imaging device, which makes it possible to reduce the time required for imaging, and to obtain a high quality image of an entire imaging area, by enabling all objects to be inspected to be brought into focus simultaneously when imaging with 1 imaging means a plurality of objects to be inspected that have different optical path lengths to the imaging means.
A further object of the present invention is to provide a semiconductor package inspection device, which is capable of performing a coplanarity inspection of lead portions even when a semiconductor package is housed in a storage container.
A further object of the present invention is to provide a semiconductor package inspection device, which is capable of performing a lead coplanarity inspection of a semiconductor package based solely on an image by 1 camera provided either almost directly above or directly below the package surface of a semiconductor package.
A further object of the present invention is to provide a semiconductor package inspection device, which is capable of performing an upper surface inspection and a side lead portion inspection of a semiconductor package using 1 imaging means.